(1) Field of the Invention
This invention relates to a liquid crystal display device and, more particularly, to a liquid crystal display device which is capable of efficiently exhausting heat produced inside a chassis.
Rejection Heat
(2) Description of the Related Art
Recent years, emissive-type plasma display devices and non-emissive-type liquid crystal display devices, which replace CRTs (Cathode Ray Tubes), have been increasingly used as a display device.
Of them, the liquid crystal displays employ a liquid crystal panel as a transmissive-type optical modulation device, in which a lighting device (hereinafter referred to as “backlight”) is provided on the back surface to apply light to the liquid crystal panel. Then, the liquid crystal panel generates an image by controlling the transmittance of the light emitted from the backlight.
The following two types of backlight for applying light to the liquid crystal panel are known.
One of them is an edge-lit type backlight which includes light sources disposed on the right and left edges or the top and bottom edges of the liquid crystal panel and emitting light to a light guide plate for redirecting the light toward the planar direction for illumination. The other is a direct-lit type backlight which applies light from the back surface of the liquid crystal panel.
One of the features of the liquid crystal display devices provides a reduction of the thickness of the outside shape, but a thinner and lower power liquid crystal display device has been desired in recent years. A reduction in thickness of the liquid crystal display device makes it difficult to ensure an airflow path for exhausting heat produced in a chassis which defining the outside shape of the liquid crystal display device. As a result, the heat cannot be efficiently exhausted, giving rise to a temperature rise in a heat-sensitive area.
To avoid this, for example, JP-A-No. 2006-235399 discloses an edge-lit liquid crystal display device in which LEDs (Light Emitting Diodes) are used as light sources of the backlight and a light-source mounting board (LED mounting board) is connected to a thermally conductive member for removing the heat produced by the LEDs for heat exhaustion from the both surfaces of the light-source mounting board.